OBJECTIVES: To study the trends in emergency department (ED) visits due to opioid abuse from 1996 to 2007 in United States. METHODS: ED visits attributable to opioid abuse were identified using diagnosis codes (ICD-9-CM codes: 304.0, 304.7, 305.5 and 965.0) from the National Hospital Ambulatory Medical Care Survey. Annual rate of ED visits for opioid abuse per 1000 people was estimated. To increase estimation precision, data from two consecutive years were pooled. Bivariate analysis and logistic regression were performed to examine the associations of patient demographic characteristics to ED visits for opioid abuse. Data were analyzed using STATA 9.2 accounting for complex survey design. RESULTS: Of the total 1,289,529,680 estimated ED visits made during the 12-year period, 1,633,224 (0.13%) were attributable to opioid abuse. ED visits for opioid abuse increased from 70,748 visits per year (0.08%) in 1996-1997 to 208,378 (0.18%) in 2006-2007. The annual rate of ED visit for opioid abuse per 1000 people increased from 0.26 in 1996-1997 to 0.70 in 2006-2007, with an estimated 8% annual increase (p<0.001). Children and elderly were less likely to have an ED visit for opioid abuse compared to nonelderly adults aged 34-64(AOR 0.075, 95% CI 0.042-0.134; AOR 0.067, 95% CI 0.026-0.173 respectively). Females were less likely to have an ED visit for opioid abuse than males (AOR 0.555, 95% CI 0.443-0.695).Compared to the West, people in the South and Midwest were less likely to have an ED visit for opioid abuse (AOR 0.447, 95% CI 0.313-0.638; AOR 0.517, 95% CI 0.334-0.799 respectively). Risks of ED visits for opioid abuse more than doubled in years 2002-2003 and 2006-2007 (AOR 2.286, 95% CI 1.420-3.679; AOR 2.329, 95% CI 1.473-3.682 respectively) compared to 1996-1997. CONCLUSIONS: The number and rate of ED visits for opioid abuse increased over time with the highest in 2006-2007.